Hide layer edit state buttons on relation editor when in transaction

... because that the buttons are there was mainly triggered by the fact
that it's sometimes hard to find the appropriate layer in the legend.

Fix #15102

Author: m-kuhn

src/gui/qgsrelationeditorwidget.cpp

@@ -24,6 +24,8 @@
 #include "qgsgenericfeatureselectionmanager.h"
 #include "qgsrelation.h"
 #include "qgsvectorlayertools.h"
+#include "qgsproject.h"
+#include "qgstransactiongroup.h"
 
 #include <QHBoxLayout>
 #include <QLabel>
@@ -199,6 +201,17 @@ void QgsRelationEditorWidget::setRelations( const QgsRelation& relation, const Q
   if ( !mRelation.isValid() )
     return;
 
+  mToggleEditingButton->setVisible( true );
+
+  Q_FOREACH ( QgsTransactionGroup* tg, QgsProject::instance()->transactionGroups().values() )
+  {
+    if ( tg->layers().contains( mRelation.referencingLayer() ) )
+    {
+      mToggleEditingButton->setVisible( false );
+      mSaveEditsButton->setVisible( false );
+    }
+  }
+
   connect( mRelation.referencingLayer(), SIGNAL( editingStarted() ), this, SLOT( updateButtons() ) );
   connect( mRelation.referencingLayer(), SIGNAL( editingStopped() ), this, SLOT( updateButtons() ) );